exec: bail out on mixed type expressions

Since our vectorized projection and selection operators currently only
handle homogeneous types, I added logic to the planner which detects
mixed types and errors out.

Fixes cockroachdb#38798

Release note: None

pkg/sql/distsqlrun/column_exec_setup.go

@@ -543,6 +543,9 @@ func newColOperator(
 func planSelectionOperators(
 	ctx *tree.EvalContext, expr tree.TypedExpr, columnTypes []semtypes.T, input exec.Operator,
 ) (op exec.Operator, resultIdx int, ct []semtypes.T, err error) {
+	if err := assertHomogeneousTypes(expr); err != nil {
+		return op, resultIdx, ct, err
+	}
 	switch t := expr.(type) {
 	case *tree.IndexedVar:
 		return exec.NewBoolVecToSelOp(input, t.Idx), -1, columnTypes, nil
@@ -583,12 +586,6 @@ func planSelectionOperators(
 		if err != nil {
 			return nil, resultIdx, ct, err
 		}
-		if !ct[leftIdx].Identical(&ct[rightIdx]) {
-			err = errors.Errorf(
-				"comparison between %s and %s is unhandled", ct[leftIdx].Family(),
-				ct[rightIdx].Family())
-			return nil, resultIdx, ct, err
-		}
 		op, err := exec.GetSelectionOperator(typ, cmpOp, rightOp, leftIdx, rightIdx)
 		return op, resultIdx, ct, err
 	default:
@@ -603,6 +600,9 @@ func planSelectionOperators(
 func planProjectionOperators(
 	ctx *tree.EvalContext, expr tree.TypedExpr, columnTypes []semtypes.T, input exec.Operator,
 ) (op exec.Operator, resultIdx int, ct []semtypes.T, err error) {
+	if err := assertHomogeneousTypes(expr); err != nil {
+		return op, resultIdx, ct, err
+	}
 	resultIdx = -1
 	switch t := expr.(type) {
 	case *tree.IndexedVar:
@@ -693,18 +693,38 @@ func planProjectionExpr(
 	if err != nil {
 		return nil, resultIdx, nil, err
 	}
-	if !ct[leftIdx].Identical(&ct[rightIdx]) {
-		err = errors.Errorf(
-			"projection on %s and %s is unhandled", ct[leftIdx].Family(),
-			ct[rightIdx].Family())
-		return nil, resultIdx, ct, err
-	}
 	resultIdx = len(ct)
 	op, err = exec.GetProjectionOperator(typ, binOp, rightOp, leftIdx, rightIdx, resultIdx)
 	ct = append(ct, *typ)
 	return op, resultIdx, ct, err
 }
 
+// assertHomogeneousTypes checks that the left and right sides of an expression
+// have identical types. (Vectorized execution does not yet handle mixed types.)
+// For BinaryExprs, it also checks that the result type matches, since this is
+// not the case for certain operations like integer division.
+func assertHomogeneousTypes(expr tree.TypedExpr) error {
+	switch t := expr.(type) {
+	case *tree.BinaryExpr:
+		left := t.TypedLeft().ResolvedType()
+		right := t.TypedRight().ResolvedType()
+		result := t.ResolvedType()
+		if !left.Identical(right) {
+			return errors.Errorf("BinaryExpr on %s and %s is unhandled", left, right)
+		}
+		if !left.Identical(result) {
+			return errors.Errorf("BinaryExpr on %s with %s result is unhandled", left, result)
+		}
+	case *tree.ComparisonExpr:
+		left := t.TypedLeft().ResolvedType()
+		right := t.TypedRight().ResolvedType()
+		if !left.Identical(right) {
+			return errors.Errorf("ComparisonExpr on %s and %s is unhandled", left, right)
+		}
+	}
+	return nil
+}
+
 // wrapWithVectorizedStatsCollector creates a new exec.VectorizedStatsCollector
 // that wraps op and connects the newly created wrapper with those
 // corresponding to operators in inputs (the latter must have already been

pkg/sql/logictest/testdata/logic_test/vectorize

@@ -400,3 +400,15 @@ query O
 SELECT * FROM t38754
 ----
 1
+
+# Test integer division. (Should fall back due to decimal result.)
+query T
+SELECT a/b FROM a WHERE b = 2
+----
+0.5
+
+# Test mixed types comparison. (Should also fall back.)
+query I
+SELECT b FROM a WHERE b < 0.5
+----
+0